feat: add daily request limit with custom toast notification (#167)

- Add DAILY_REQUEST_LIMIT env var support in config API
- Track request count in localStorage (resets daily)
- Show friendly quota limit toast with self-host/sponsor links
- Apply limit to send, regenerate, and edit message actions

app/api/config/route.ts

@@ -8,5 +8,6 @@ export async function GET() {
 
     return NextResponse.json({
         accessCodeRequired: accessCodes.length > 0,
+        dailyRequestLimit: parseInt(process.env.DAILY_REQUEST_LIMIT || "0", 10),
     })
 }